#include <iostream>
#include <queue>
using namespace std;

typedef pair<int, int> PII;

int main()
{
    queue<PII> q;

    for (int i = 0; i < 10; i++)
    {
        q.push({i, i * 10});
    }
    
    while(q.size())
    {
        auto t = q.front();
        q.pop();
        cout << t.first << " " << t.second << endl;
    }
    return 0;
}